A Chemical Oxygen Demand (COD) test is used to measure the oxygen equivalent of the organic matter in a sample that is susceptible to oxidation by a strong chemical oxidant. In the Open Reflux Method, the organic matter is oxidized by a boiling mixture of chromic and sulfuric acids. In a known method of performing the COD test a glass vial having premeasured reagents is supplied, and the sample is added to the glass vial. One known glass vial for use in a COD test is generally shaped like a test tube with a screw-on cap. The test tube is provided with reagents, and the sample to be tested is added to the reagents after removing the cap. The cap is replaced, and the reaction proceeds to completion in a heated digester block. The test tube is then placed in a spectrophotometer to complete the test.
Other glass vials of various types and other containers known in the prior art are shown in U.S. Pat. Nos. 4,559,052, 4,266,681, 3,688,812, 4,134,511, 4,481,297, 1,224,231, 2,517,604, 3,459,185, and 4,254,883. Similarly, many types of closures suitable for closing ampules or vials have been disclosed in the prior art. Some examples are provided by U.S. Pat. Nos. 3,085,705, 4,884,707, 4,379,647, 4,196,820, 4,481,297, and Can. 617,018.
The prior art vials/ampules present several disadvantages in at they are expensive to manufacture and difficult to use. For example, vials/ampules must be made of materials that do not interfere with the test. In the vial described above that uses a screw-on cap, the cap is lined with a Teflon coating to prevent reaction between the reagents and the material of the cap, which would interfere with the testing of the sample. And, the manufacture of the threaded neck requires thick glass, which is quite expensive.